The forum plans to invest $20,000 in full-page ads and a direct mail campaign in support of the Nov. 5 referendum being quietly spearheaded by Mayor Alex Penelas. The mayor is using a low-key, community-outreach approach to selling the initiative.

"We want the voters to hear from the business community and not just the county campaigners," said Mario Artecona, forum executive director. "They should have another perspective than the party line."

The forum, a coalition of the county’s business leaders, issued a statement saying "congestion and gridlock, a limited rapid transit system and an aging bus system – combined with projected population growth – will limit our ability to compete with other metropolitan areas."

"If we don’t do this we’re putting a noose around our necks," Mr. Artecona said. "But the return on our investment if it passes will be to the economic engine that is transportation in South Florida."

The initiative, dubbed "The People’s Transportation Plan" by Mayor Penelas’ administration, calls for a half-percent sales tax increase to collect about $150 million annually to add buses, trains and rail lines and expand rapid-transit service. It includes a citizen oversight board to audit use of transit-tax funds.

If approved by voters, transit planners would begin phasing in portions of a 30-year plan to double the bus fleet, add 90 miles of rail lines and overhaul major roads and highways. Metrorail service is proposed to run 24 hours while the downtown Metromover service would become free.

While research shows Miami-Dade County voters may support a transit tax if they know what it would provide, public opinion experts say the average resident may not hear the message if Mayor Penelas remains opposed to a mass-media campaign.

Instead of educating voters via mass media, the county is running a grassroots campaign targeting business, civic and community organizations throughout the county, a move some experts see as narrow and preaching to the already converted.

But the mayor says a higher-profile campaign could do more harm than good because voters in 1999 rejected a 1% transportation tax amid perceptions of special interest lobbying.

"The last time (1999) the transit proposal came up, the public awareness campaign became the issue and not the transit tax," he said last week before speaking in support of the plan to a gathering of real estate representatives.

Not all public opinion experts agree.

"The grassroots meetings are great, but without collateral support, it looks like a stealth campaign. That plays back into the sense that there is trickery afoot," said Robert A. Ladner, president of Coral Gables-based Behavioral Science Research.

Dr. Ladner, who during the summer surveyed 850 registered voters on transit-financing attitudes, also said a strictly grassroots campaign may not reach the critical mass of voters needed to pass the measure.

"People need to know about it. Show them the map," he said, referring to visual ads that could illustrate new transit lines and services.

"As soon as we brought out a map of proposed new lines, interest went up and skepticism went down," he said, recalling a recent focus group study on the issue. "There’s nothing like a map with colors, tracks and extension plans to turn a pipedream into a plan," at least in voters’ minds.

Dario Moreno, director of the Metropolitan Center at Florida International University, supported the effectiveness of visual mass media.

"The problem with community outreach is that it works in a special campaign with small voter turnouts. But when there is huge turnout, like the one expected Nov. 5, people tend to go into the booth and vote no to things they don’t understand. It’s like, first do no harm," he said.

"I think they chose the grassroots approach not because it makes the most sense but because it will do the least damage. The mayor and the civic leadership got so burned in 1999 that the last thing they want is a high-profile campaign," Dr. Moreno said.

According to Dr. Ladner’s research, commissioned by the county, the most staunchly opposed demographic group to a transit tax plan is non-Hispanic Anglos, particularly in South Miami-Dade.

"These persons see the high proportions of Hispanics in positions of leadership in the county as evidence of corruption," the study’s summary of ethnic differences said. It also reported that Anglos are most likely be transit non-users and doubt whether there is anything in the initiative that addresses their needs.

Dr. Ladner’s research also found that Hispanics and blacks generally showed more enthusiasm toward the transit tax, though skepticism and feelings of being disenfranchisement could arise.